Modified:
Correctly preparing aluminum for the application of paint or for surface repair is essential in the aerospace industry. AMS 2473, “Chemical Film Treatment for Aluminum Alloys, General Purpose Coating,” is the accepted standard for this process. And now it’s available in the updated Revision H, just released at the end of September.
Why use this standard? It increases the corrosion resistance of aluminum alloy parts. It is a great base for paint and other organic finishes. And it can be used to prep parts for repair of abraded surfaces or discontinuous anodized coatings.
Working with the chemicals involved is hazardous. While the document doesn’t address those dangers directly, it reminds the user to ensure that the folks working with this process are familiar with the safe and proper use of the materials involved.
Of course, you’ll also remember that other processes like heat-treating, joining and other finishing operations can affect your use of the standard. You’ll make sure to get an engineer to review the sequence of events when more than 1 process is involved.
AMS 2473 has been updated as a result of the 5 year review of the standard. Since the last edition was Revision G from 2002 (reaffirmed in 2007), it’s been a while. The committee has not alerted the user to where the changes reside.
If you’re interested in applications that include electrical bonding, you’ll want to use AMS 2477 instead. This standard, “Conversion Coating for Aluminum Alloys, Low Electrical Resistance Coating,” is currently Revision A from 2010. It basically replaced the AMS 2474 standard in 2006.
Many organizations rely on the MIL-DTL-5541, “Chemical Conversion Coatings on Aluminum and Aluminum Alloys,” for chemical conversion coatings as well. FYI: It’s similar to ISO 8081, “Aerospace Process – Chemical Conversion Coating for Aluminium Alloys – General Purpose.”
The challenge here is Rohs compliance. This EU Directive requires organizations to remove certain hazardous chemicals from products sold in Europe. The hexavalent chromium that is used in these processes is a barrier to conformance.
To purchase these standards, go to the Document Center web store — www.document-center.com. You’ll find them all available in paper format or for pdf download. Or you are welcome to contact us by phone (650-591-7600), fax (650-591-7617) or email (info@document-center.com). We support your use of correct documentation with sales and monitoring services, as well as current awareness and reporting products. You can trust your standards collection to us — we’re your Standards Experts!
